Throttle for free-piston units



8 1947- w. A. LEDWITl-l 2,426,311

THROTTLE FOR FREE-PISTON UNITS Filed July 23, 1.943 2 Sheets-Shoot 2 INVENTOR 44% 4.

GUI/MM ATTORNEY I Patented Aug. 26, 1947 THROTTLE FOR FREE-PISTON UNITS Walter A. Ledwith, Hartford, Conn, assignor to United Aircraft Corp oration, East Hartford,

Conn, a corporation of Delaware Application July 23, 1943, Serial No. 495,935

In throttling a part of a double-acting free-piston engine-and-compressor unit in adapting it for compressing a gaseous medium of greater density, throttles are provided for closing off the intake to one end of the compressor cylinder as disclosed in the copending Kalitinsky application, Serial No. 495,918, filed July 23, 1943. In this application the compressor has a number of intake Passages for the inner ends of the compressor,.

with a separate throttle in each passage.

A problem in throttling one end of the compressor cylinder is to close all the intake passages so that the compressor will function as a singleacting unit. A feature of this invention is to provide for interlocking the several throttles so that they will all open or close as a unit, thereby assuring a complete closing of the intake passages.

Many free-piston engines have opposed pistons for balancing the unit in which event the inner ends of the compressor cylinders must be throttled simultaneously in adapting the unit to a higher pressure or density. Another feature of the comattached to the compressor pistons complete the.

reciprocating piston assemblies. The sleeves in combination with stationary pistons 28 and 30 form air spring cylinders.

The piston assemblies are moved apart by the burning of fuel injected into engine cylinder H) Air compressed in the air spring cylinders on the power stroke returns the piston assemblies. The assemblies are always maintained at equal distances from the center of the engine cylinder by a linkage, which may include racks 34 extending from the compressor pistons and engaging opposite sides of a pinion 36.

Intake manifold 38 conducts air to intake valves 4|] through which air alternately enters opposite ends of the compressor cylinders. -The compressed air leaves the cylinders through discharge valves 42, also at opposite ends of the com- 2 Claims. (01. 230-56 pressor cylinders, and passes through scavenge manifold 44 through ports 46 and 48 which are uncovered by pistons l2 and M at the end of the power stroke, thereby permitting air to be blown through the engine cylinder and exhaust ports 50 and 52 into exhaustmanifold 54.

When an increase inthe density of a medium being pumped has shortened the strokes of'the pistons, the change in density is compensated for by throttling the intake to the inner ends of the compressor cylinders. Pairs of valves 55 and 53 close the passages and 62 leading from intake manifold 38 to the chamber 64 which comby which rod 66 with the throttles thereon may be turned.

The pair of valves 5c are mounted on a rod 18 extending parallel to rod 456 and also journaledin lugs on the compressors. Rod 18 has a projecting arm 60 connected by a link 32 to an arm 84 on extension shaft Hi. In this way turning shaft ill by arm M closes both pairs of valves 56 and it simultaneously.

It is to be understood that the invention is not limited to the specific embodiment herein illustrated and described, but may be used in other ways without departure from its spirit as defined by the following claims. v

I claim:

1. A free-piston engine-and-compressor unit including an engine cylinder, opposed pistons therein, spaced compresso cylinders located at opposite ends of the engine cylinder, and a histon in each compressor cylinder connected to and moving with the adjacent engine piston, in combination with a supporting structure interconnecting said compressor and engine cylinders and having passages for admitting fluid to one end of rods mounted for turning in the unit, each rod having mounted thereon at least two of the throttles, a connection between the rods to cause the necting said compressor and engine cylinders and having passages for admitting fluid to one end of each compresso cylinder, and means for throttling the fiow of fluid through said passages to said one end of each compressor, said means including throttles in each of said passages, each throttle being substantially in the form of a disc adapted to fit within and close a substantially cylindrical portion of the associated passage, a'

pair of rods on which said throttles are mounted, each rod supporting at least a pair of throttles, a connection between the rods to cause them to turn simultaneously and one of said rods projecting outside of the unit to provide for turning the rods for adjusting the position of the throttles.

. WALTER A. LEDWITH.

REFERENCES CITED The following references are of record in the file of this patent:

Number Number UNITED STATES PATENTS Name Date Pescara Feb, 6, 1940 Wainwright Aug. 22, 1939 Crittenden Aug, 25, 1936 Noble July 11, 1939 Tamberton May 26, 1936 Halleck Nov. 15, 1927 Gess Sept. 15, 1942 Hirsch Aug. 7, 1934 Pescara Mar. 30, 1937 Muller Dec. 22, 1942 Raven Sept. 30, 1902 Norton et a1 Mar. 17, 1908 Nordberg Oct. 6, 1908 Gehres Aug. 7, 1934 Steiner Aug, 24, 1937 Steiner Dec. 6, 1938 Renick Feb. 18, 1941 Steiner Feb. 21, 1939 FOREIGN PATENTS Country Date Great Britain 1926 Switzerland 1937 

